Polishing and abrading materials



July 12, 1966 w. F. ZIMMER, JR, ETAL 3,250,582

POLISHING AND ABRADING MATERIALS Filed March 24, 1964 INVENTORS. WILLIAM R IMMERA LE gv E. OOGSTOEL ATTORNEY United States Patent 3,260,582 POLISHING AND ABRADING MATERIALS William F. Zimmer, Jr., Elnora, and Leon E. Hoogstoel, Schenectady, N .Y., assignors to Norton Company, Troy, N.Y., a corporation of Massachusetts Filed Mar. 24, 1964, Ser. No. 354,473 12 Claims. (Cl. 51-293) The present invention relates in general to fibrous polishing and/ or abr-ading materials and more particularly to such materials formed from continuous or substantially continuous synthetic filaments.

It has heretofore been proposed to form polishing pads with or without included abrasive materials from synthetic fibers and natural fibers of various kinds. The art has followed a trend towards the use of synthetic fibers as such materials have become more readily available since many of these fibers are not water-sensitive, are extremely tough and durable, and in general possess more desirable characteristics than do the natural fibers. Early efforts to produc polishing materials utilized cotton, jute, sisal fibers or the like as illustrated in the patents to Hurst, US. 2,284,738 and to Loefiler, U.S. 2,327,199. Following the development of equipment capable of producing randomly oriented fiber webs such as the Rando-Webber machine marketed by the C-urlator Corporation of R0- chester, New York and described in US, Letters Patent Nos. 2,541,915; 2,700,188; 2,703,441 and 2,744,294 commercial webs produced on this machine for various textile purposes (as illustrated by Maisel, US 2,784,132) were adapted for polishing pads as illustrated by Hoover et al. US. 2,958,593.

All of these webs suffered from various defectschief among which was the tendency for delamin-ation or separation of the fibers or layers of fibers from one another in use. Efforts to overcome this lack of strength as by the use of a binder adhesive for the fibers and a rollcoated harder adhesive overlying the binder adhesive as shown in Camp et al. U.S. 3,020,139, while imparting definite improvements in life and performance did not completely solve the problem. Polishing pads still tended to tear rather readily and, in the case of polishing or scouring pads used under rotating floor machines, the problem of destruction of the pads when a sharp or projecting edge was encountered by the edges of the pad remained acute.

An object of the invention is the provision of a new and improved method of making non-woven polishing materials.

An additional object is the provision of an improved method of making high loft non-woven material.

It is also an object of this invention to provide a method for increasing the impregnation of non-woven polishing pads with adhesive and/ or adhesive and abrasive particles.

Additional objects, if not specifically set forth herein, will be readily apparent to one skilled in the art from the following detailed description of the invention:

In the drawings:

FIGURE 1 is a perspective view, in partial section, of a circular polishing pad made by the method of the present invention.

FIGURE 2 is an enlarged plan view of a small section of the surface of the pad shown in FIGURE 1, illustrating the directional nature of the filaments and the degree of interlocking achieved.

FIGURE 3 is a schematic diagram of one apparatus set up for practicing the method of the present invention.

Generally, the present invention resides in the formation of a non-woven polishing material from substantially continuous filaments wherein such filaments are treated to impart a permanent crimp or curl thereto, straightened 3,260,582 Patented July 12, 1966 out under tension into a substantially parallel relationship with one another, uniformly coated while under tension with an adhesive which may or may not contain abrasive particles, interlocked one with another by release of such tension and then set in a permanently interlocked and lofty, open, three-dimensional state by curing or setting-up of the adhesive.

More specifically, the use of long continuous filaments instead of the short or relatively short fibers of the prior art imparts a high degree of internal strength to the nonwoven polishing materials of the present invention. While preferably directional in the sense that the filaments of any given layer in a multi-layer product made in accordance with this invention extend generally in the same direction, the non-woven material has all of the interlocking or intersecting of one filament with the others necessary to achieve the advantages of prior art random Webs due to the interconnection of the crimps or curls imparted to each of th filaments prior to coating with the bonding adhesive. Because the adhesive binder is applied to the filaments while they are in a stretched, relatively parallel and non-intersecting relationship, each filament receives a uniform coating of the binder and, if abrasive particles such as abrasive grains ar included in the adhesive, th distribution of the abrasive is much more uniform than can be achieved by spraying or otherwise incorporating abrasive into a preformed web. The webs so formed are lofty and three-dimensional in nature since the filaments, when tension is released, expand both laterally and vertically as the crimps imparted to the filaments spring back into existence. The degree of loftiness can be controlled by the filament density, i.e., the number and diameter of the filaments per linear unit in the width direction of the web.

Referring now to the drawings, FIGURE 1 illustrates a circular polishing pad 10 formed of a plurality of continuous synthetic filaments 11, each having many crimps or curls 12 interconnecting and entwining with the crimps or curls of adjacent filaments. Each of the filaments 11 is uniformly coated with a layer of adhesive 13 which serves to hold the filaments bonded to one another at each point of intersection of one filament with another. As illustrated in FIGURE 1, the adhesive 13 contains a plurality of abrasive grains 14 which are uniformly distributed both along the filaments 11 and throughout the thickness of the pad 10. The abrasive grains 14 are held firmly to the filaments 11 by the adhesive 13.

The general relationship of the filaments 11 to each other is more clearly shown in FIGURE 2 wherein an enlarged section of the top surface 15 of pad 10 is shown. This view also clearly shows the uniform distribution of the adhesive 13 and abrasive grains 14 along the fibers 11.

While a number of variations of equipment for producing the non-woven polishing materials of the present invention may be employed, the schematic diagram of FIGURE 3 is illustrative of the preferred method. The filaments 11 are drawn directly from an extrusion bath or from a warp beam or from any suitable source (not shown) in the form of a plurality of substantially parallel strands through a set of idler rolls 16 and 17 and thence over a heated blade 18 which preferably consists of a sharp edged blade set at a sharp angle to the direction of travel of the filaments 11. The blade 18 may, if desired, be heated by any suitable means such as a resistance element heater 19, for example to a temperature of about 250 F. which has been found suitable for nylon filaments of 15-150 denier. Other temperatures may be used as desired for different synthetic filaments or filaments of different deniers, but generally the temperature must be low enough to avoid actual melting or thermal decomposition of the material. Since the contact with the blade is for an extremely limited period of time (filament speeds of 25 ft./minute and over being preferred), the blade temperature generally is not too critical. Both temperature and speed are interdependent and will vary somewhat depending upon filament diameter. Contact of the blade 18 with the filaments 11 imparts a pronounced and permanent crimp or curl in the filament. This permanent crimp or curl appears to result from straining the filaments or a portion thereof beyond the elastic limit but below the point of fracture. A filament, treated in this fashion may be stretched out straight but when tension is relaxed it will assume its crimped configuration once again. After passing over the crimping blade 18, the filaments 11 still in their substantially parallel relationship to one another are passed through an adhesive-applying station 20. This station may take the form of spray heads or, as is illustrated, a roll coating bath 20. The parallel filaments 11 pass over idler rollers 21 and 22 and through the bath 20 of adhesive 13. The filaments 11 now coated with adhesive 13 pass through squeeze rolls 25 and 26 which remove the excess adhesive and are then allowed to relax as they exit from the squeeze rolls. The crimps 12 built into the filaments now appear and cause the filaments 11 to interlock with each other to form the lofty web 27. This web deposits on any suitable surface, preferably a conveyor 28 as shown in FIGURE 3 and is passed through a heating zone 29 to set up or cure the adhesive 13 which bonds filaments 11 together at each point of intersection of the crimps 12. The conveyor 28 operates at a speed slow enough to permit the desired depth of filament accumulation and since a single layer is generally not contemplated, additional lines of which 30 is merely representative feed their webs 27, made up of similarly coated filaments 11' having crimps 12', onto the web 27 on conveyor 28. These additional webs 27 may be fed by rolls 25 and 26 either parallel to the direction of web 27 or preferably at some angle thereto as illustrated in FIGURE 3 to impart multidirectional strength to the laminate of webs so formed. If desired the filaments in some or all of the subsequent layers of webs may be laid in a twisting or sinusoidal path dependent entirely upon the properties desired in the finished web. The crimps 12 coated with adhesive 13 act to interlock the superposed web 27' with web 27 in the same manner that they act to interlock the adjacent filaments 11. While not shown in FIGURE 3, obviously the bath 23 may contain abrasive grains in the form of a slurry with the adhesive 13. Obviously, abrasive may be also added to webs produced in accordance with the above after the adhesively-bonded web is cured where uniform abrasive distribution is not a requirement. The finished web 31 is rolled up as at 32 for conversion into finished products as described in connection with the Camp et a1. patent, US. 3,020,139. Obviously, the cure in zone 29 may be left incomplete so that the web 31 is still tacky when rolled as at 32 so that upon completion of the adhesive cure the roll is self-sustaining and the convolutions thereof are adhesively bonded one to the other. Alternatively, the cure is completed in zone 29 and the web 31 is non-tacky and can readily be unwound from roll 32 for further conversion into sheets, discs or the like as desired.

Filaments bulked by methods other than the knife-edge curling described above are also suitable for use in this invention. For example, the crimp may be produced by passing the filaments through a stuifer box (a device which comprises a mechanism for feeding the filaments into a crimping chamber which is maintained full of filaments under a predetermined back pressure and temperature) wherein the filaments, as they are forced into the crimping chamber, are laid in zig-zag form and pressed to form angular bends or crimps with intervening straight portions. When the filaments emerge from the stuffer box they are cooled to set the crimp and then stretched under tension to disentangle the filaments and temporarily acquire a largely two-dimensional crimp. In general, the

type of crimping method used the process of the present invention is not critical except that it is preferred that at least a portion of the crimp imparted to the filaments should be of relatively high amplitude and three-dimensional in character. Further, in order that the filaments intermesh and cross one another and form many contact points for subsequent {adhesive bonding, it is desired that the stretched filaments have crimps or curl of such character as to cause, on relaxation of tension, the length direction to shrink at least about 10% and preferably more.

While the present invention contemplates preferably using only continuous filaments in forming the non-woven web, it is entirely within the scope of the invention to add other textile materials in the form of short fibers, flock or the like to the web along with the continuous filament in those instances where it may be so desired. These additive fibers may range in length from a fraction of an inch to several inches or more and will be adhesively bonded to the continuous filament-s and to each other at their points of intersection.

Also, while the process is described above in conjunction with the crimping of the filaments, obviously precrimped filaments may be used and the orimp temporarily pulled out under tension as the adhesive or adhesive and abrasive grain slurry in applied.

The preferred filaments used in the present invention are poly-amides, such as nylon, or polyester filaments. Other flexible, tough, synthetic, organic filaments capable of being lthermoformed and which can be used include the vinylidenes, olefins, fluorocarbons, arcylonitriles and acrylics. The filament diameter is not oritcia-l and any desired denier or mixture of denie-rs may be employed as desired. Generally, the filaments found most useful are of 15 denier or coarser up to about 300 microns in diameter.

The adhesives used to bond the filaments may vary from the elastomeric to the hard, heat-advancing resinous type. Generally, where the web is not to include abrasive, the adhesive type will depend upon the degree of firmness or stiffness desired in the finished product with the elastomeric adhesives giving the most flexible web. Where the radehsive used to bond the filaments is also to be used to hold abrasivegrain to the filaments or where a relatively stiffer web is desired, such adhesive general- 1y is selected from the heat-advancing resinous types such as the polyurethane or phenol-aldehyde-based adhesives. The adhesives, abrasive grain types and sizes, chemical nature and diameters of the filaments are all of the genenal character known to the art and are as disclosed in the aforesaid Camp et al. patent, US. 3,020,139.

The term continuous filaments as used herein is intended to indicate that the filaments are substantially continuous and much longer than the /2 to 3" fibers heretofore used in commercial products of this general nature. Obviously, when the webs made in accordance with this invention are cut or died out to form polishing anticles, the filaments are cut and cease to be continuous. It can therefore be generalized that products made in accordance with the present invention are characterized by the presence of continuous adhesive-coated filaments at all portions thereof other than the peripheral boundaries of the product.

The present invention permits, as described above, both more uniform and also greater quantities of adhesive and/ or adhesive and abrasive to be incorporated into the finished web. Prior art pre-fiormed webs (as for example that disclosed in Hoover et al. US. 2,958,593) do not permit uniform abrasive distribution since the web fibers act as a filter, stnaining out the grain and keeping its concentration much higher at the outside surface of the web. Likewise, binding is non-uniform in such webs with the centers having less adhesive and a consequent tendency to delaminate. The present invention uniformly coats each filament prior to forming the Web and thus much greater uniformity of coat is possible. Furthermore, whereas prior art webs must be limited in thickness due to the need to pass adhesive or slurry through the web, the present invention is completely unlimited as to Web thickness.

Obviously, many variations and modifications can be made without departing from the spirit and scope of the invention as disclosed herein so that the only limitations to be inferred are those set forth in the appended claims.

We claim:

1. A method for the manufacture of a non-woven polishing material which comprises: holding under tension a plurality of continuous pre-crimped synthetic filaments arranged in substantially parallel relationship with one another; applying a substantially uniform coating of adhesive to said filaments while under tension; relaxing the tension on said adhesive-coated filaments before said adhesive dries to permit said filaments to return to their crimped sate with the crimps in each filament intersecting and entwining with the crimps of adjacent filaments; and setting the adhesive coating to anchor said filaments to each other at their points of intersection.

2. A method for the manufacture of a non-woven polishing material which comprises: arranging a plurality of continuous, pro-crimped synthetic filaments in closely spaced parallel relationship; applying tension to said filaments to temporarily remove the crimps therefrom; applying a substantially uniform coating of adhesive to said filaments while under tension; relaxing the tension on said adhesive-coated filaments before said adhesive dries to permit said filaments to return to their crimped state with the crimps in each filament intersecting and entwining with the crimps of adjacent filaments; and setting the adhesive coating to anchor said filaments to each other at their points of intersection.

3. A method for the manufacture of a non-woven polishing material which comprises: arranging a plurality of continuous, synthetic filaments in closely spaced parallel relationship; imparting a tendency to crimp to said filaments while held in said parallel relationship; aplying tension to said filaments to temporarily keep said crimp from reveloping; aplying a substantially uniform coating of adhesive to said filaments while under tension; relaxing the tenison on said adhesive-coated filaments before said adhesive dries to permit the development of crimps therein with the crimps in each filament intersecting and entwining with the crimps of adjacent filaments; and setting the adhesive coating to anchor said filaments to each other at their points of intersection.

4. A method for the manufacture of a non-woven polishing material which comprises: holding under tension a plurarilty of continuous pre-crimped synthetic filaments arranged in substantially parallel relationship with one another; applying a substantialy uniform coating of adhesive to said filaments while under tension; relaxing the tension on said adhesive-coated filaments before said adhesive dries to permit said filaments to return to their crimped state with the crimps in each filament intersecting and entwining with the crimps of adjacent filaments; repeating this procedure with at least one other layer of filaments arranged in parallel relationships out of phase with said first-mentioned filaments; depositing said other layer of filaments on top of said first-mentioned filaments, the crimps of said other layer interlocking with the crimps of said first-mentioned filaments; and setting 6 the adhesive coating to anchor said filaments to each other and to the filaments of adjacent layers.

5. A method for the manufacture of a non-woven polishing material which comprises: arranging a plurality of continuous, pre-crimped synthetic filaments in closely spaced parallel relationship; applying tension to said filaments to temporarily remove the crimps therefrom; applying a substantially uniform coating of adhesive to said filaments while under tension; relaxing the tension on said adhesive-coated filaments before said adhesive dries to permit said filaments to return to their crimped state with the crimps in each filament intersecting and entwining with the crimps of adjacent filaments; repeating this procedure with at least one other layer of filaments arranged in parallel relationships out of phase with said first-mentioned filaments; depositing said other layer of filaments on top of said first-mentioned filaments, the crimps of said other layer interlocking with the crimps of said first-mentioned filaments; and setting the adhesive coating to anchor said filaments to each other and to the filaments of adjacent layers.

6. A method for the manufacture of a non-woven polishing material which comprises: arranging a plurality of continuous, synthetic filaments in closely spaced parallel relationship; imparting a tendency to crimp to said filaments while held in said parallel relationship; applying tension to said filaments to temporarily keep said crimp from developing; applying a substantially uniform coating of adhesive to said filaments while under tension; relaxing the tension on said adhesive-coated filaments before said adhesive dries to permit the development of crimps therein with the crimps in each filament intersecting and entwining with the crimps of adjacent filaments, repeating this procedure with at least one other layer of filaments arranged in parallel relationships out of phase with said first-mentioned filaments; depositing said other layer of filaments on top of said first-mentioned filaments, the crimps of said other layer interlocking with the crimps of said first-mentioned filaments; and setting the adhesive coating to anchor said filaments to each other and to the filaments of adjacent layers.

7. A method (for the manufacture of a non-woven polishing material which comprises: holding under tension a plurality of continuous pre-crimped synthetic filaments arranged in substantially parallel relationship with one another; applying a substantially uniform coating of adhesive and abrasive grains to said filaments while under tension; relaxing the tension on said adhesive-coated filaments before said adhesive dries to permit said filaments to return to their crimped state with the crimps in each filament intersecting and entwining with the crimps of adjacent filaments; and setting the adhesive coating to anchor said filaments to each other at their points of intersection and to bond the abrasive grains along each of said filaments.

8. A method for the manufacture of a non-woven polishing material which comprises: arranging a plurality of continuous, pre-crim-ped synthetic filaments in closely spaced parallel relationship; applying tension to said filaments to temporarily remove the crimps therefrom; applying a substantially uniform coating of adhesive and abrasive grains to said filaments While under tension; relaxing the tension on said adhesive-coated filaments before said adhesive dries to permit said filaments to return to their crimped state with the crimps in each filament intersecting and entwining with the crimps of adjacent filaments; and setting the adhesive coating to anchor said filaments to each other at their points of intersection and to bond the abrasive grains along each of said filaments.

9. A method for the manufacture of a non-woven polishing material which comprises: arranging a plurality of continuous, synthetic filaments in closely spaced parallel relationship; imparting a tendency to crimp to said filaments while held in said parallel relationship; applying tension to said filaments to temporarily keep said crimp from developing; applying a substantially uniform coating of adhesive and abrasive grains to said filaments while under tension; relaxing the tension on said adhesivecoated filaments before said adhesive dries to permit the development of crimps therein with the crimps in each filament intersecting and entwining with the crimps of adjacent filaments; and setting the adhesive coating to anchor said filaments to each other at their points of intersection and to bond the abrasive grains along each of said filaments.

10. A method for the manufacture of a non-woven polishing material which comprises: holding under tension a plurality of continuous pre-crimped synthetic filaments arranged in substantially parallel relationship with one another; applying a substantially uniform coating of adhesive and abrasive grains to said filaments While under tension; relaxing the tension on said adhesive-coated filaments before said adhesive dries to permit said filaments to return to their crimped state with the crimps in each filament intersecting and entwining with the crimps of adjacent filaments; repeating this procedure with at least one other layer of filaments arranged in parallel relationships out of phase with said first-mentioned filaments, depositing said other layer of filaments on top of said first-mentioned filaments, the crimps of said other layer interlocking with the crimps of said first-mentioned filamets; setting the adhesive coating to anchor said filaments to each other and to the filaments of adjacent layers and to bond the abrasive grains along each of said filaments.

11. A method for the manufacture of a non-woven polishing material which comprises: arranging a plurality of continuous, pre-crimped synthetic filaments in closely spaced parallel relationship; applying tension to said filaments to temporarily remove the crimps therefrom; applying a substantialy uniform coating of adhesive and abrasive grains to said filaments While under tension; relaxing the tension on said adhesive-coated filaments before said adhesive dries to permit said filaments to return to their crimped state with the crimps in each filament intersecting and entwining with the crimps of adjacent filaments; repeating this procedure with at least one other layer of filaments arranged in parallel relationships out of phase with said first-mentioned filaments; depositing said other layer of filaments on top of said first-mentioned filaments, the crimps of said other layer interlocking with the crimps of said first-mentioned filaments; setting the adhesive coating to anchor said filaments to each other and to the filaments of adjacent layers and to bond the abrasive grains along each of said filaments.

12. A method for the manufacture of a non-woven polishing material which comprises: arranging a plurality of continuous, synthetic filaments in closely spaced parallel relationship; imparting a tendency to crimp to said filaments while held in said parallel relationship; applying tension to said filaments to temporarily keep said crimp from developing; applying a substantially uniform coating of adhesive and abrasive grains to said filaments while under tension; relaxing the tension on said adhesive-coated filaments before said adhesive dries to permit the development of crimps therein With the crimps in each filament intersecting and entwining with the crimps of adjacent filaments; repeating this procedure with at least one other layer of filaments arranged in parallel relationsips out of phase with said first-mentioned filaments; depositing said other layer of filaments on top of said first-mentioned filaments, the crimps of said other layer interlocking with the crimps of said first-mentioned filaments; setting the adhesive coating to anchor said filaments to each other and to the filaments of adjacent layers and to bond the abrasive grains along each of said filaments.

References Cited by the Examiner UNITED STATES PATENTS 2,958,593 11/1960 Camp et al. 5l295 3,016,294 1/1962 Haywood 51-297 3,020,139 2/1962 Hoover et al. 51-295 3,116,986 1/1964 Goepfert et al 51297 3,147,575 9/1964 Shnabel 5140O 3,175,331 3/1965 Klein 51400 ROBERT C. RIORDON, Primary Examiner. L. S. SELMAN, Assistant Examiner. 

1. A METHOD FOR THE MANUFACTURE OF A NON-WOVEN POLISHING MATERIAL WHICH COMPRISE: HOLDING UNDER TENSION A PLURALITY OF CONTINUOUS PRE-CRIMPED SYNTHETIC FILAMENTS ARRANGED IN SUBSTANTIALLY PARRALLEL RELATIONSHIP WITH ONE ANOTHER, APPLYING A SUBSTANTIALLY UNIFORM COATING OF ADHESIVE TO SAID FILAMENTS WHILE UNDER TENSION, RELAXING THE TENSION ON SAID ADHESIVE-COATED FILAMENTS BEFORE SAID ADHESIVE DRIES TO PERMIT SAID FILAMENTS TO RETURN TO THEIR CRIMPED SATE WITH THE CRIMPS IN EACH FILAMENT INTERSECTING AND ENTWINING WITH THE CRIMPS OF ADJACENT FILAMENTS, AND SETTING THE ADHESIVE COATING TO ANCHOR SAID FILAMENTS TO EACH OTHER AT THEIR POINTS OF INTERSECTION. 